Transluminal coronary angioplasty was introduced in the late 1970's as a nonsurgical treatment for obstructive coronary artery disease. Since its introduction, major advances in equipment and techniques have led to widespread use of the method for treating coronary artery disease and angina.
In a typical endovascular procedure the treatment device is brought in close proximity to the lesion. Because the diseased vessels are narrowed and often tortuous, the device must be able to navigate through tortuous vasculature and cross through tight lesions. For example, in an angioplasty procedure, typically a balloon catheter is advanced coaxially over a guidewire and forced through the lesion prior to dilation. In photodynamic therapy (PDT), a light source, typically a fiber optic needs to be brought to the lesion site where a photoinitiator compound was selectively taken up. In addition, the light needs to uniformly deliver over a relatively long length (˜2 cm) requiring the need of optical diffusers to spread out the light delivered through the fiber or fiber bundle.
Despite improvements in equipment and techniques, restenosis persists as the limiting factor in the maintenance of vessel patency in angioplasty, occurring in 30% to 50% of patients, and accounting for significant morbidity and health care expenditures. Post-angioplasty restenosis is a segmentally limited, wound healing response to a traumatization of the vascular wall.